1. Field of the Invention
The present invention relates to a loading mechanism suitable for use in a recording or reproducing apparatus.
2. Description of the Related Art
In a conventional recording or reproducing apparatus for recording video information on a magnetic tape or reproducing recorded video information, detecting means for detecting the motion of a tension detecting arm provided with a tension detecting roller for detection of a tape tension has been secured to a main chassis, whereas a tape has not been consistently kept in contact with the tape detecting roller during loading. For such reasons, it has been impossible to activate a tension detecting mechanism until a complete tape path is formed after the completion of the loading, with the result that it has been impossible to detect an abnormal tension which may occur during loading/unloading.
To solve the above problems, a proposal has been made in U.S. patent application Ser. No. 690,648 filed on Apr. 24, 1991. The outline of the proposal is shown in FIG. 1. The proposed arrangement includes tape guiding means 57 for detecting a tape tension, a tape-tension detecting arm 70 supported for rotation at one end thereof and provided with the tape guiding means 57 at the other end, elastic supporting means 68 for elastically supporting the arm 70 in one rotational direction, and position detecting means 74 for detecting the motion of the arm 70. The elastic supporting means 68 and the position detecting means 74 are disposed on a common loading plate 63. The loading plate 63 is also provided with elastic means 71 for maintaining a tape 55 in consistent contact with the tape guiding means 57 while the tape 55 is being loaded/unloaded.
With the above-described arrangement, it may be possible to solve the above problems of the conventional recording or reproducing apparatus. However, in such an arrangement, load is consistently applied to the elastic means 71 during loading or unloading and, in addition, a large load is applied during unloading when compared to during loading. Accordingly, to cause the aforesaid mechanism to operate stably, it is necessary to reinforce a loading driving member and a loading motor. As a result, it has been difficult to further miniaturize the apparatus.
In general, many types of recording or reproducing apparatus employ motors as driving sources for implementing tape loading. However, since the stop position of such a motor tends to fluctuate, it has been difficult to determine accurately a position where a tape guide for detection of a tape tension is to be located when unloading is completed. For this reason, there has been a risk that the tape guide interferes with a cassette half, a tape reel or the tape wound around the tape reel. To solve such a problem, a loading unit is provided with a charging mechanism, and overcharging is performed upon completion of unloading.
However, such a mechanism has a complicated structure and requires a considerable area for installation, and it has been difficult to further miniaturize the apparatus as far as the mechanism is used.